During the coming year the principal investigator will initiate studies on the role of catecholamines and prostaglandins in puppies and adult dogs utilizing the radioimmune assay developed in his laboratory. These techniques will also allow for investigations on the precursors of prostaglandins such as arachidonic acid. To separate the possible effect of vascular responses to the prostaglandins a series of experiments will be conducted in dog kidneys previously treated with smooth muscle relaxants such as papaverine. Finally, studies will be begun on spontaneously hypertensive rats to compare the effect of a catecholamine inhibitor, 6-hydroxydopamine, on renal hemodynamics.